Telephone receiver



Sept. 20, 1927. ,1 9

A. NYMAN TELEPHONE RECEIVER Filed Dec. '7, 1923 If a 4 I x 1 Y 1 Q a g-6 4, i In g 2 anon H601 Patented Sept. 20, 1927.

UNITED STATES PATENT OFFICE.

ALEXANDER NYMAN, or EAST ORANGE, NEW JERSEY, ASSIGNOR 'ro DUBILIERconnnnsna coaroaa'rron, on NEW YORK, N. "2., A conroaarion'or DELAWARE.

TELEPHONE RECEIVER.

Application filed December 7, 1923. Serial No. 679,147.

This invention relatesto improvements in telephone receivers and moreparticularly to improvements in the construction of telephone loudspeakers.

6 It is the object of the present invention to provide a compact andsimple receiver of the dynamic type. With this object in view, I providea receiver in which the pole pieces of the magnet structure are in closeproximity to each other, an intense direct current field being providedby magnetizing a. centrally located leg of a substantially annularpermanent magnet. Variations in this field are produced by means of atransformer coil which is held within the air gap of the magnetstructure. The means-by which the receiver diaphragm is vibrated isarranged to move within this air gap.

' These and other features of the present invention will more clearlyappear from the following detailed description of two exemplificationsof the invention and the appended claims.

"In the drawings, Figs. 1 and 2 are sectional side views of twoembodiments of the present invention.

Referring first to Fig. 1, a casing I mounted on a base 2 encloses thereceiver structure comprising a permanent magnet 3. A substantiallycylindrical wall 4 is fastened to the permanent magnet 3 by means ofscrews 5 or forms an integral part thereof. This permanent magnet has anupwardly projecting cylindrical leg 6 centrally provided with respect tothe wall 4; and carrying a suitable energizing winding 7 provided withinthe cylinder 4 and connected with a direct current source, (not shown).The upper end of the cylindrical wall 4 carries a laminated pole piece 8of-silicon steel or other material having a very high permeability. Thisannular pole piece 8 is welded or otherwise secured to the wall 4. Anannular transformer coil is provided at 9 and held frictionally insideof the pole piece 8. The conductors through which the telephoniccurrents are transmitted are connected to this stationary coil. The endof the leg 6 of the magnet structure is surrounded by a substantiallybell shaped cap or annular member 10 of aluminum or other light materialsuitably fastened to a diaphragm 11. The diaphragm 11 is clamped bymeans of a bell shaped holder 12 for born 13 against a ring 14 which inturn is mounted on the upper end of the casing 1.

It will be seen therefore that the cylinder or cap 10 is traversed by arelatively strong direct current ma netic field produced by means of thewinding 7. This cap 10 is exposed also to alternating current induced bythe speech currents through the agency of theannular coil 9 which willcause said cap to move up and down and thus to vibrate the diaphragm 11.

The structure disclosed in Fig. 2 is substantially like the one shown inFig. 1 except that in addition to the laminated pole piece 8 provided onthe wall 4, a similar pole piece 20 surrounds the upper end of the leg6. Furthermore, the transformer coil 9 is wound around the pole piece 20and is surrounded by the bell shaped cap 10. The operation of the deviceshown in this figure is the same as in the above case.

The annular pole pieces 8 and 20 are substantially concentric with thecoil 9 so that the lines of force of the magnetic flux due to the coil 9are parallel with the height of these annular laminations, that is tosay,

parallel with the axis of these laminations and of the coil 9 where saidlines of force pass through the laminations. In practice, thelaminations should not be in the form of continuous rings, but should becut in an axial direction so that the annular laminations are notshort-circuited.

As will be understood, the variations of flux in the magnetic fieldcreate considerable losses in solid magnetic pole pieces. I thereforeprovide near the magnetic air gap the laminated parts 8 and 20 throughwhich the alternating flux can pass freely without causing excessivehysteresis, or eddy current losses. With such a construction thealternating magnetic flux will be localized in these magnetic parts,while the permanent magnetic flux may continue to flow freely at rightangles to the laminations.

Obviously, the magnetizing coil 7 for the permanent magnetic field maybe omitted if the material for the magnet is of such nature as to retainits magnetization and form a permanent magnet. Such material isnecessarily conducive to high hysteresis losses,

but with the alternating flux localized in the laminated parts, theselosses will not take place in my invention.

What 1 claim is:

1. In a telephone receiver, a magnet com prising opposite poles, atransformer coil cooperating with said poles, and a laminated pole pieceassociated with at least one of said poles and surrounding said coil,said pole piece having its laminations substantially parallel to theportions of the lines of force of the flux due to the action of saidcoil which pass through said pole piece.

2. In a telephone receiver, a magnet comprising opposite poles, atransformer coil cooperating with said poles, and a laminated pole pieceassociated with at least one of said poles and having its laminationsarranged to be substantially parallel with the portions of the lines offorce of the flux due to the action of said coil which pass through thelaminations. a diaphragm and a cap secured to said diaphragm andsubstantially concentric with said pole piece and said coil.

3. In a telephone receiver, a magnet structure comprising a permanentmagnet having a leg subject to direct current magnetization providedbetween and in close proximity to the pole pieces of said permanentmagnet, an annular laminated pole piece at the end of said leg, and atransformer coil wound around said last mentioned pole piece.

4. In a telephone receiver, a magnet structure comprising a cylindricalwall anda central leg the free end of which is in close proximity to thefree end of said wall, a direct current energizing winding on saidcentral leg and within said wall, an annular laminated pole piecesecured to the upper end of said cylindrical wall, an annulartransformer coil held Within said pole piece, an aluminum cylindersuspended between said transformer and the free end of said leg, and adiaphragm on which said aluminum cylinder is mounted.

In a telephone receiver, a base, a casing thereon enclosing a magnetstructure con1- prising a cylindrical wall and a central leg the freeend of which is in close proximity to the free end of said wall, adirect current energizing winding on said central leg and w thin saidwall, two annular laminated pole pieces, one withinthe other and securedto the upper ends of said cylindrical wall and leg, respectively, anannular transformer coil provided between said pole pieces, an aluminumcylinder suspended between said transformer and one of said pole pieces,a diaphragm on which said aluminum cylinder is mounted, and means forclamping said diaphragm to said casing.

6. In a telephone receiver an annular pole piece, a cylindrical polepiece cooperating therewith, a transformer coil associated with one ofsaid pole pieces, means for localizing the alternating magnetic fluxproduced by said transformer coil, an annular metallic member betweensaid pole pieces, and a sound producing body connected to said member.

7. In a telephone receiver, a magnetic structure comprising an annularpole piece, a cylindrical pole piece cooperating therewith, atransformer coil associated with one of said pole pieces, meanscomprising laminated sheets of magnetic metal associated with saidtransformer coil, an annular 1netallic member between said pole pieces,and a sound producing body connected to said member.

In testimony whereof I aflix my signature.

ALEXANDER NYMAN.

